Last night I saw The Avengers and loved it. I had my doubts about it when I found out they were going to fight aliens but it ended up working out perfectly. There were a lot of parts that were really obvious that they were going to happen including the ending, and a lot of parts when it made you say "why didn't they do that in the first place?" My friends and I thought it was pretty stupid that we were supposed to know who hawkeye was. There were a few funny parts thrown into the movie and they were all really funny. All of the action parts were great but it got annoying with some of the camera angles like when it randomly went sideways for some reason.
I didn't see the Thor or Captain America movies but it didn't hinder my enjoyment of the movie not knowing any of their back story, but it did make me want to watch the movies. Despite its flaws i still thought it was one of the best super hero movies and I highly recommend you watch it.